1. Field of the Invention
This invention relates generally to an apparatus for the protection of cables and posts (or columns) against the dynamic loads from rolling stones, vehicular impact, ice impact or other forms of transient loads and, more particularly, the invention relates to a CNC impact load deflector sleeve and removable collar installable on the cable holding the fence post, which, in turn, stretches rock fall drape net, which constitutes a rock fall mitigation fence system (RFMFS).
2. Description of the Prior Art
A rock fall mitigation fence (RFMF) is frequently used to protect the traveling vehicles against potential hazards of falling rocks. The fence system is composed of the fence cable, fence posts, and rock fall drape net resting on the cable, which, in turn, is stretched and supported on the fence posts and cable anchors. The fence posts are embedded in rock and the cable is connected to the ground anchor embedded in rock. The RFMFS functions as a flexible fence system for retaining falling rocks by dissipating their dynamic energy during the back and forth swing upon rock impact. The mass of falling rocks varies a great deal. It can range from a few hundred pounds to many tons.
When falling from the hill/mountain top or slope, a falling rock gains momentum as it rolls down the slope. When it comes in contact with a RFMFS, the rock rotates at an extremely high angular velocity, can sever fence-supporting cables, and knocks out or severely bends fence posts, cuts anything it touches. The failure of the RFMFS allows the falling rocks to land on the highway or, in some cases, on top of a moving vehicle, as demonstrated in the rock fall in Georgetown, Colo. on Apr. 8, 2004. To date the only mechanism for the failure prevention of the RFMFS is to use stronger nets, cables and posts. The literature search including the search on the US Patent and Trademark web site and the communication with fence installers did not reveal any other fence cable or post protection apparatuses as the CNC Impact Load Deflector Sleeve (CNC//ILDS) and Removable Collar (RC) submitted in this invention that deflect the moving rocks and impact force, and, thereby, reduce the chance of cable and post failures. Accordingly there exists a need for a mechanism for deflecting falling rocks and impact force, reducing the chance of fence failure and enhancing the safety of the traveling public.